Mr. Lupez misunderstood his statement and thought that he was responsible for the $91.70 charge from his visit. He sent a check in that amount. The workers' compensation company also sent a payment of $80.00. Both payments were posted to Mr. Lupez's account. As the charge for the office visit and Tdap immunization were the only charges on his account, these two payments created a(n): Balance due Credit balance Negative credit Overdue account